Technical Abstract:
Maize plants are subjected to many stresses in the field during growth. Plant response to these stresses affect yield. Lesion mimics are useful to study plant reactions to stresses because the mutant plants show many symptoms of disease without the presence and complications of a causal organism. Many lesion mimics show variation in severity in different genetic backgrounds. Lesion mimics tend to be more severely expressed in early-senescence backgrounds and less severely expressed in stay-green backgrounds. Stay-green backgrounds have also been reported to provide drought tolerance. The goal of my research was to identify quantitative trait loci (QTL) controlling differential expression of lesion mimics in specific genetic backgrounds. A hsl*-1 lesion mimic in a severe-expressing line was crossed to Mo20W, a lesion-suppressing, stay-green line. A QTL analysis was performed to detect significant loci for modification of lesion expression. A locus with a highly-significant effect was found on chromosome 2 that delayed the lesion phenotype by more than 20 days and significantly decreased lesion severity. The discovery of a significant QTL in our genetic model for plant disease may aid in improving plant response to lesion stress, and possibly allow tolerance to other conditions that adversely affect yield.